Meeting in Amsterdam, heads of the fifteen EU member states finalized a treaty amending the Maastricht Treaty, strengthening common foreign and security policy, incorporating the Schengen Agreement into EU law, and expanding the powers of the European Parliament. Signed formally in October 1997, it took effect in 1999 and marked a significant step toward deeper European political integration.
The Amsterdam summit capped months of difficult negotiation among EU members still digesting the sweeping changes of the 1992 Maastricht Treaty, which had created the euro currency framework and the modern European Union structure. Amsterdam sought to fix perceived weaknesses, particularly around decision-making ahead of planned eastward expansion into former Communist states.
The treaty folded the Schengen free-movement zone into the EU's legal architecture, gave the European Parliament greater co-legislative power, and created the position of a High Representative for foreign policy, an early step toward a more unified European voice on the world stage.
Critics at the time complained the treaty ducked harder questions about institutional reform needed for enlargement, issues that would resurface in the Nice and Lisbon treaties. Still, Amsterdam represented a durable expansion of Brussels' authority into areas once guarded jealously by national governments, particularly justice and home affairs, foreshadowing the EU's growing role in migration policy.